Indirectly Referencing a Cell on a Different Worksheet

@David Robinson:

I also can't help you to get INDIRECT to work correctly when it refers to a closed workbook. There is a similar problem with the 4 very helpful functions COUNTIF, COUNTIFS, SUMIF, and SUMIFS. Imagine, for instance, the formula =COUNTIF('[Other Workbook.xlsx]Books'!$K:$K,"Y"). This works properly if the other workbook is open, but if it is not, it will return #VALUE!. Just to make things more confusing, if Other Workbook is open when you enter the formula, it will return the right value; if you close it, that correct value is cached but any other similar formulae you enter will get the #VALUE!. The COUNT, COUNTA, and SUM functions don't have this problem.

An alternative (to COUNTIF) would be to use an array formula of the SUM function: {=SUM( ('[Other Workbook.xlsx]Books'!$K:$K="Y") * 1)}
You could of course use "+ 0" instead of "* 1" in the formula if you'd rather. In either case, the bit inside the inner parens will return an array of TRUE and FALSE values, the * 1 or + 0 turns those into 1 or 0, and the count of TRUE values is identical to the sum of the 1's. I'll leave as an exercise for the reader how to use the same trick to replace the COUNTIFS, SUM, and SUMIFS functions.

Here's an example: i opened "Other Workbook", then entered in "This Workbook", cells A1:B2, the COUNTIF formula in cell A1 and the SUM formula in B1. Both return the correct value. I then closed "Other Workbook", and entered the same formulae on row 2. You can see that the value 708 was cached in cell A1 even though the formula is no longer valid. If you force cell A1 to be recalculated, it will change to #VALUE!, and an Undo won't heal it. In any case, the SUM formula in column B work just fine.

708..............708
#VALUE!......708

Because this workaround literally only occurred to be this morning, I've always used "transfer sheets" to deal with this problem - I'd add a worksheet to "Other Workbook" and put all my COUNTIFS and SUMIFS functions there, with a simple "hard link" from "This Workbook". This is probably what you meant by "using a lot of spreadsheet real estate". Considering that the COUNTIFS and SUMIFS formulae are easier to understand than the SUM workaround, I'll probably continue to use them and pay the price of using transfer sheets.

@David Robinson:

Here's one suggestion (see the Tip's text):
=IFERROR(INDIRECT("'"&A1&"'!B11"),"Please open "&A1)

You can test for a 'not "G"' format in an IFERROR(), taking the date information if it succeeds in the "usual ways" to provide out to INDIRECT(). And you can have the error result take it as is. You can also wrap all that in another IFERROR() that handles things of an even more unusual nature.

The nested IFERROR() approach can be used lots of places. For some reason, that never seems to come up when it is talked about.

As far as those apostrophes go (for names with spaces), having them when the name is a single word causes NO problems, so just use a formula containing them to handle either of the two situations that might occur. Never bother with not putting them in.

Unfortunately I can only use INDRECT to point at a cell in an *open* workbook. If I close the file I'm pointing to, the INDIRECT will no longer work (returns #REF!).

I've used various workarounds in the past, most of which use a lot of spreadsheet real estate but do at least work, and of course I can use a macro to set the formula to do the pointing (i.e. the macro sets the cell's formula to a conventional reference using the text that would've been the INDIRECT argument), but can anyone advise if it's possible just using formulas to get INDIRECT to work on a closed workbook?

Re. "Because the apostrophes are used to enclose a worksheet name, you cannot have any text in cell A1 that includes apostrophes." I believe this formula will accommodate a name that includes apostrophes:

=IFERROR(INDIRECT("'"&SUBSTITUTE(A1,"'","''")&"'!B11"),"No Data")

In this case, two apostrophes will be substituted for each apostrophe in cell A1 to determine the INDIRECT address.

And since a worksheet's name can include leading and/or trailing space characters, it might not be a good idea to use the TRIM function.

INDIRECT is powerful when combined with ADDRESS, which lets you do math to select which cells to reference.